How to fix it, depends on what's broken, I'd say. If you don't have a service contract for it the best thing to do is call HP and arrange a repair.

How to configure a consumer grade router is detailed in the manual that came with it. For a professional router it might be better to have it done by the supplier.

Do I understand your company has a vacancy for an IT-guy? Or maybe they'd better outsource the system management.

Kees